If someone drowns with you attacking them you get RP, they get Necro (most of the time), shame for them, not really a problem for you though is it?
If someone runs away and escapes then they need to run all the way (normaly to cs) to regroup with everyone instead of just getting killed and spawning there, and your RP count is a bit lower

Its Rp, who cares?
Have to agree that both of these are no less cheap/sad/cowardly etc than hunters coming from camo with ambush, confuse etc ... more so on low level grinders, yes I still see level 50 hunters hunting level 30-40's. You brave people
I have never seen a syrtian drown themself that I can remember, probably because people are often alone when they do it, I have however seen Alsius and Ignis do it countless times so dont doubt Syrtis do it as well. Just because you dont see your realm do something, dosnt mean they dont.
In conclusion, its a the same RP for you, necro for them, or a few less RP, big deal.